In the vending machine and soft drink dispensing industry it is well known that a basic problem exists with regard to increasing the flow rate of dispensed liquids above the standard one and one-half to three ounces per second. This basic problem manifests itself in excessive foaming of the drink, which causes spillage and overflow. In addition, excessive foaming reduces the efficiency of the operator responsible for dispensing the drinks, because excessive foaming requires the operator to terminate the filling cycle early to permit foam reduction, then re-initiate the filling cycle to "top off" the drink.
Nevertheless, it is desirable that flow rates be maximized to reduce the time required to dispense the soft drink, thus providing improved customer service or reducing the number of attendants required at the work station. Increased flow rate drink dispensers are particularly desirable at high-volume operations such as movie theaters and amusement parks.
Conventional diffusers and spouts used with existing dispensing equipment do not function well when scaled up to flow rates of 5 ounces per second or more. Using conventional equipment, when the flow rate is increased to in excess of 3 ounces per second undesirable hissing occurs at the spout or excessive foaming results from the mixing that occurs between the carbonated water and the syrup. Furthermore, of high flow rates quality of the drink is known to decrease because of stratification of the syrup or excessive loss of carbon dioxide.
It is known that high pressure carbonated water, typically in the range of 60-120 PSIG, used with conventional dispensing equipment, must gently be reduced to atmospheric pressure so as to lose a minimum of carbon dioxide. In existing equipment the methods of pressure reduction result in excessive out-gassing of the carbon dioxide at high flow rates, thus causing excessive foaming of the drink with the attendant reduction in efficiency of the operator and waste of the product. Also, this excessive out-gassing results in a "flat" drink.
Various methods have been previously devised to reduce foaming of the drink yet attempt to maintain the quality of the drink. The most conventional method to reduce foaming of the drink is to provide a restricted passage in the flow, thus reducing the velocity of the carbonated water. However, by placing a restriction in the line the flow rate is substantially reduced to undesirable levels. In other dispensing devices a coiled feed line is provided to reduce foaming of the dispensed soft drink. Alternatively, it is possible to provide a series of chambers which are operative to reduce the pressure of carbon dioxide in the water at various stages in the diffuser and spout assembly. However, this approach has led to an excessive out-gassing of the carbon dioxide, thus resulting in an undesirable reduction in the quality of the dispensed drink.
Existing diffusers and spout assemblies normally contain an inlet for the carbonated water and an inlet for the syrup. These inlets open into chambers which eventually meet at a common mixing chamber. The common mixing chamber opens into a spout for dispensing of the carbonated water/syrup mixture. A pressure reduction occurs at the first chamber, where the carbonated water or syrup is introduced, again at the mixing chamber and again at the spout. Thus, in conventional diffusers and spout assemblies pressure reduction occurs generally at only 2 or 3 locations, the result being a limitation in the potential flow rate, or if the chambers are made large enough to facilitate higher flow rates, an undesirable out-gassing of carbon dioxide from the carbonated water.